Hybrid fiber grating cavity for multi-parametric sensing.

We propose an all-fiber hybrid cavity involving two unbalanced uniform fiber Bragg gratings (FBGs) written at both sides of a tilted FBG (TFBG) to form an all-fiber interferometer. This configuration provides a wavelength gated reflection signal with interference fringes depending on the cavity features modulated by spectral dips associated to the wavelength dependent optical losses due to cladding mode coupling occurring along the TFBG. Such a robust structure preserves the advantages of uniform FBGs in terms of interrogation methods and allows the possibility of simultaneous physical and chemical sensing.